Abstract
PURPOSE: Recovery of lymphocyte populations after lymphocyte depletion is implicated in therapeutic immune pathways in animal models and in patients with cancer. We sought to evaluate the effects of chemotherapy-induced lymphodepletion followed by granulocyte-macrophage colony-stimulating factor (GM-CSF) and high-dose interleukin-2 (IL-2) therapy on clinical response and the recovery of lymphocyte subcompartments in patients with metastatic melanoma. PATIENTS AND METHODS: This was a two-stage phase II trial design. Patients with measurable metastatic melanoma were treated with intravenous cyclophosphamide (60 mg/kg, days 1 and 2) and fludarabine (25 mg/m(2), day 3 through 7) followed by two 5-day courses of intravenous high-dose bolus IL-2 (600,000 U/kg; days 8 through 12 and 21 through 25). GM-CSF (250 microg/m(2)/d beginning day 8) was given until granulocyte recovery. Lymphocyte recovery profiles were determined by flow cytometric phenotyping at regular intervals, and clinical outcome was assessed by Response Evaluation Criteria in Solid Tumors (RECIST). RESULTS: The trial was stopped at the end of stage 1 with four of 18 objective responses noted. Twelve patients had detailed lymphocyte subcompartments evaluated. After lymphodepletion, we observed an induction of regulatory cells (CD4+ T regulatory cells; CD8+ T suppressor cells) and of T memory cells (CD8+ T central memory cells; T effector memory RA+ cells). Expansion of circulating melanoma-specific CD8(+) cells was observed in one of four HLA-A2-positive patients. CONCLUSION: Chemotherapy-induced lymphodepletion modulates the homeostatic repopulation of the lymphocyte compartment and influences recovering lymphocyte subpopulations. Clinical activity seems similar to standard high-dose aldesleukin alone.